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Finding Critical Values. In Exercises 5鈥�8, find the critical value \({{\rm{z}}_{{{\rm{\alpha }} \mathord{\left/

{\vphantom {{\rm{\alpha }} {\rm{2}}}} \right.

\kern-\nulldelimiterspace} {\rm{2}}}}}\)that corresponds to the given confidence level.

99.5%

Question:In Exercises 5鈥�8, use the given information to find the number of degrees of freedom, the critical values X2 L and X2R, and the confidence interval estimate of $蟽$. The samples are from Appendix B and it is reasonable to assume that a simple random sample has been selected from a population with a normal distribution.

Heights of Men 99% confidence;n= 153,s= 7.10 cm.

Cell Phone Radiation Here is a sample of measured radiation emissions (cW/kg) for cell phones (based on data from the Environmental Working Group): 38, 55, 86, 145. Here are ten bootstrap samples: {38, 145, 55, 86}, {86, 38, 145, 145}, {145, 86, 55, 55}, {55, 55, 55, 145}, {86, 86, 55, 55}, {38, 38, 86, 86}, {145, 38, 86, 55}, {55, 86, 86, 86}, {145, 86, 55, 86}, {38, 145, 86, 556}.

a. Using only the ten given bootstrap samples, construct an 80% confidence interval estimate of the population mean.

b. Using only the ten given bootstrap samples, construct an 80% confidence interval estimate of the population standard deviation.

Using Correct Distribution. In Exercises 5鈥�8, assume that we want to construct a confidence interval. Do one of the following, as appropriate: (a) Find the critical value $t_{\frac{伪}{2}}$ ,(b) find the critical value $z_{\frac{伪}{2}}$,or (c) state that neither the normal distribution nor the t distribution applies.

Birth Weights Here are summary statistics for randomly selected weights of newborn girls:$\mathbf{n}鈥�\mathbf{=}鈥�\mathbf{205}\mathbf{,}\stackrel{\mathbf{炉}}{\mathbf{x}}鈥�\mathbf{=}\mathbf{30}\mathbf{.}\mathbf{4}鈥�\mathbf{hg}\mathbf{,}\mathbf{s}鈥�\mathbf{=}\mathbf{7}\mathbf{.}\mathbf{1}鈥�\mathbf{hg}$ (based on Data Set 4 鈥淏irths鈥� in Appendix B). The confidence level is 95%.

Finding Critical Values. In Exercises 5鈥�8, find the critical value $z_{\frac{伪}{2}}$that corresponds to the given confidence level.

98%

Normality Assessment A random sample consists of 48 times (min) required for American Airlines flights to taxi out for takeoff. All of the flights are American Airlines flights from New York (JFK) to Los Angeles and they all occurred in January of a recent year. The 48 taxi-out times are depicted in the histogram and normal quantile plot shown below. Based on those graphs, does it appear that the taxi-out times are from a population having a normal distribution? Give an explanation for the distribution shown. Do the taxi-out times appear to satisfy the requirements necessary for construction of a confidence interval estimate of the standard deviation of the population of all such times?

Wristwatch Accuracy Use the sample data from Exercise 7 鈥淲ristwatch Accuracy鈥� and construct a 95% confidence interval estimate of $蟽$.

Degrees of Freedom In general, what does 鈥渄egrees of freedom鈥� refer to? For the sample data described in Exercise 7 鈥淩equirements,鈥� find the number of degrees of freedom, assuming that you want to construct a confidence interval estimate of $渭$ using the t distribution.

Finding Critical Values. In Exercises 5鈥�8, find the critical value \[{{\rm{z}}_{{{\rm{\alpha }} \mathord{\left/

{\vphantom {{\rm{\alpha }} {\rm{2}}}} \right.

\kern-\nulldelimiterspace} {\rm{2}}}}}\]that corresponds to the given confidence level.

98%

In Exercises 6鈥�10, assume that women have diastolic blood pressure measures that are normally distributed with a mean of 70.2 mm Hg and a standard deviation of 11.2 mm Hg (based on Data Set 1 鈥淏ody Data鈥� in Appendix B).

Diastolic Blood Pressure Find \({{\bf{P}}_{{\bf{90}}}}\), the 90th percentile for the diastolic blood pressure levels of women.